CN204697021U - A kind of multimedia active loundspeakers control circuit - Google Patents

Abstract

The utility model provides a kind of multimedia active loundspeakers control circuit, comprise: preamplifying circuit and rear class power amplification circuit, described preamplifying circuit comprises audio input interface and volume tone control circuit, the output of described audio input interface connects volume tone control circuit, the output of described volume tone control circuit connects rear class power amplification circuit, and the output of described rear class power amplification circuit connects output loudspeaker.The utility model, by arranging Dolby circuit, limits input impedance, avoids preamplifying circuit to be in high impedance status, suppresses alternating current impression signal, improves the signal to noise ratio of system.Rear class power amplification circuit amplifies the audio signal of input for receiving described prime and amplifies, and drives, realize the control exported audio signal to the readiness control circuit of rear class amplification work.

Description

A multimedia active audio control circuit

technical field

The utility model relates to a sound, in particular to a multimedia active sound control circuit.

Background technique

As a music playback device, the audio system is deeply loved by consumers. At present, the audio system known to people mainly realizes its playback function by connecting with various audio source devices, such as connecting with VCD, MP3, and computers. However, this type of audio system generally requires Connecting to an external power source is inconvenient to carry, so it is inconvenient to play anytime and anywhere. If you want to play outside, you need to carry a power supply separately, or you need to find a location where the mains power can be transferred to play, which severely limits the scope of use. At present, for most audio power amplifier chips, there are certain requirements for the load of the speaker. In order to achieve better audio output quality, when the speaker is made of a material with a small load resistance, it is more likely to cause a large load on the speaker and damage the speaker. The problem, and then there will be a large current back in series to damage the audio power chip, which will greatly limit the application range of the audio power amplifier chip.

Utility model content

In order to overcome the above-mentioned problems in the prior art, the utility model provides a multimedia active audio control circuit.

The technical solution adopted by the utility model is: a multimedia active audio control circuit, which is characterized in that it includes: a pre-stage amplifier circuit and a rear-stage power amplifier circuit, and the pre-stage amplifier circuit includes an audio input interface and a volume tone control circuit , the output end of the audio input interface is connected to the volume and tone control circuit, the output end of the volume and tone control circuit is connected to the subsequent power amplifier circuit, and the output end of the latter power amplifier circuit is connected to the output speaker.

Further, the volume tone control circuit is composed of an operational amplifier IC1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a capacitor C2, the audio input interface is connected to one end of the input resistor R1, the The other end of the resistor R1 is connected in series with the resistor R2 to the negative input terminal of the operational amplifier IC1, the positive input terminal of the operational amplifier is grounded, and a resistor R4 is set between the negative input terminal and the output terminal of the operational amplifier. The output terminal of the amplifier is connected with the said post-stage power amplifying circuit through the resistor R5 and the adjustable resistor VR1.

Further, the input end of the volume tone control circuit is also provided with a noise reduction circuit composed of a capacitor C1 and a resistor R6, one end of the parallel connection of the capacitor C1 and the resistor R6 is connected to the output end of the audio input interface, and the other end is grounded.

Further, the post-stage power amplifying circuit includes a standby control circuit and an audio signal output circuit, the output terminal of the standby control circuit is connected to the audio signal output circuit, and the output terminal of the audio signal output circuit is connected to a speaker.

Further, the standby control circuit includes a triode Q1, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C7, the collector of the triode Q1 is connected to the control terminal of the subsequent amplifier circuit through a resistor, and the resistor R15 It is connected in series with capacitor C7, one end is connected to the power supply, and the other end is grounded, the collector of the triode Q1 is connected to the power supply through the resistor R12, the base of the triode Q1 is connected to the power supply through the voltage dividing resistor R13, and one end of the resistor R14 is connected to the power supply. The base of the transistor Q1 is connected, the other end is grounded, and the emitter of the transistor Q1 is grounded.

Further, the audio signal output circuit includes an audio power amplifier IC2 and a negative feedback circuit composed of resistors R8 and R9, the standby control circuit is connected to the audio power amplifier, and a negative feedback circuit is set on the audio power amplifier.

The beneficial effects of the utility model are: the utility model limits the input impedance by setting the noise reduction circuit, avoids the high impedance state of the preamplifier circuit, suppresses the AC induction signal, and improves the signal-to-noise ratio of the system. The rear-stage power amplifier circuit is used to receive and amplify the audio signal input by the pre-amplifier, and drive the standby control circuit of the rear-stage amplifier to control the output of the audio signal.

Description of drawings

Fig. 1 is a structure diagram of a multimedia active audio control circuit provided by the utility model.

Detailed ways

Below in conjunction with accompanying drawing, the utility model is described in detail.

Referring to Fig. 1, it is a structural diagram of a multimedia active audio control circuit provided by the utility model.

As shown in Figure 1, a multimedia active audio control circuit is characterized in that it includes: a pre-amplification circuit and a post-stage power amplifying circuit, the pre-amplification circuit includes an audio input interface and a volume tone control circuit, the The output end of the audio input interface is connected to the volume and tone control circuit, the output end of the volume and tone control circuit is connected to the subsequent power amplifier circuit, and the output end of the latter power amplifier circuit is connected to the output speaker.

Further, the volume tone control circuit is composed of an operational amplifier IC1, a resistor R1, a resistor R2, a resistor R3, a resistor R4, a resistor R5 and a capacitor C2, the audio input interface is connected to one end of the input resistor R1, the The other end of the resistor R1 is connected in series with the resistor R2 to the negative input terminal of the operational amplifier IC1, the positive input terminal of the operational amplifier is grounded, and a resistor R4 is set between the negative input terminal and the output terminal of the operational amplifier. The output terminal of the amplifier is connected with the said post-stage power amplifying circuit through the resistor R5 and the adjustable resistor VR1.

Further, the input end of the volume tone control circuit is also provided with a noise reduction circuit composed of a capacitor C1 and a resistor R6, one end of the parallel connection of the capacitor C1 and the resistor R6 is connected to the output end of the audio input interface, and the other end is grounded.

In the embodiment of the utility model, when the audio is turned off, the audio input interface is suspended and is in a high-impedance input state. At this time, the AC signal induced by the front stage is sent to the rear stage circuit for amplification, so that the speaker has strong noise. The noise circuit limits the input impedance, prevents the pre-amplifier circuit from being in a high-impedance state, suppresses the AC induction signal, and improves the signal-to-noise ratio of the system.

Further, the post-stage power amplifying circuit includes a standby control circuit and an audio signal output circuit, the output terminal of the standby control circuit is connected to the audio signal output circuit, and the output terminal of the audio signal output circuit is connected to a speaker.

Further, the standby control circuit includes a triode Q1, a resistor R12, a resistor R13, a resistor R14, a resistor R15, and a capacitor C7, the collector of the triode Q1 is connected to the control terminal of the subsequent amplifier circuit through a resistor, and the resistor R15 It is connected in series with capacitor C7, one end is connected to the power supply, and the other end is grounded, the collector of the triode Q1 is connected to the power supply through the resistor R12, the base of the triode Q1 is connected to the power supply through the voltage dividing resistor R13, and one end of the resistor R14 is connected to the power supply. The base of the transistor Q1 is connected, the other end is grounded, and the emitter of the transistor Q1 is grounded.

Further, the audio signal output circuit includes an audio power amplifier IC2 and a negative feedback circuit composed of resistors R8 and R9, the standby control circuit is connected to the audio power amplifier, and a negative feedback circuit is set on the audio power amplifier.

In the embodiment of the utility model, the rear amplifier circuit is used to receive and amplify the audio signal input by the former amplifier, and the power control circuit drives the standby control circuit of the latter amplifier to realize the control of the output of the audio signal .

The utility model has been introduced in detail above, but the utility model is not limited to the above-mentioned embodiments, and various changes can be made without departing from the purpose of the utility model within the scope of knowledge of those skilled in the art. Many other changes and modifications can be made without departing from the spirit and scope of the present invention. It should be understood that the invention is not limited to specific embodiments, and the scope of the invention is defined by the appended claims.

Claims (6)

1. A multimedia active audio control circuit, characterized in that it comprises: a preamplifier circuit and a rear stage power amplifier circuit, the preamplifier circuit includes an audio input interface and a volume tone control circuit, the audio input interface The output end is connected to the volume and tone control circuit, the output end of the volume and tone control circuit is connected to the power amplifying circuit of the subsequent stage, and the output end of the power amplifying circuit of the latter stage is connected to the output speaker. 2. A kind of multimedia active sound control circuit according to claim 1, is characterized in that, described volume tone control circuit is made up of operational amplifier IC1, resistance R1, resistance R2, resistance R3, resistance R4, resistance R5 and electric capacity C2 The audio input interface is connected to one end of the input resistor R1, the other end of the resistor R1 is connected in series with the resistor R2 to the negative input terminal of the operational amplifier IC1, and the positive input terminal of the operational amplifier is grounded, so A resistor R4 is set between the negative input terminal and the output terminal of the operational amplifier, and the output terminal of the operational amplifier is connected to the subsequent power amplifier circuit through the resistor R5 and the adjustable resistor VR1. 3. A kind of multimedia active audio control circuit according to claim 1, characterized in that, the input end of the volume tone control circuit is also provided with a noise reduction circuit made up of capacitor C1 and resistor R6, and the capacitor C1 and One end of the resistor R6 connected in parallel is connected to the output end of the audio input interface, and the other end is grounded. 4. A kind of multimedia active audio control circuit according to claim 1, characterized in that, said post-stage power amplifying circuit comprises a standby control circuit and an audio signal output circuit, and the output terminal of said standby control circuit is connected to an audio signal An output circuit, the output end of the audio signal output circuit is connected to a speaker. 5. A multimedia active audio control circuit according to claim 4, wherein the standby control circuit comprises a triode Q1, a resistor R12, a resistor R13, a resistor R14, a resistor R15 and a capacitor C7, and the triode Q1 The collector of the transistor Q1 is connected to the control terminal of the post-amplification circuit through a resistor, the resistor R15 and the capacitor C7 are connected in series, one end is connected to the power supply, and the other end is grounded, the collector of the transistor Q1 is connected to the power supply through a resistor R12, and the transistor Q1 The base of the resistor R13 is connected to the power supply through the voltage dividing resistor R13, one end of the resistor R14 is connected to the base of the transistor Q1, and the other end is grounded, and the emitter of the transistor Q1 is grounded. 6. A kind of multimedia active sound control circuit according to claim 4, is characterized in that, described audio signal output circuit comprises audio frequency power amplifier IC2 and the negative feedback circuit that is made up of resistance R8, R9, and described standby control The circuit is connected with the audio power amplifier, and a negative feedback circuit is set on the audio power amplifier.